Electrosurgical instrument and method of use

Abstract

Electrosurgical jaw structures are disclosed that include pressure sensitive variable resistive materials in electrosurgical energy delivery surfaces for welding tissue. The pressure sensitive materials are configured to have megaohm impedance when not engaging tissue and can transform into highly conductive electrodes when compressed under a selected pressure. In a method of the invention, the pressure sensitive variable resistive materials prevent arcing and tissue desiccation when applying bi-polar Rf current to tissue engaged under high compression in an electrosurgical jaw structure.

1 . A method of applying electrosurgical energy to tissue comprising, 
 providing an electrosurgical instrument having a jaw structure configured to engage tissue; and    applying electrosurgical energy from the jaws to engaged tissue wherein a pressure sensitive system connected to the instrument adjusts electrosurgical energy delivery in response to tissue-engaging pressure.    
   
   
       2 . The method of applying electrosurgical energy to tissue of  claim 1  wherein a pressure sensitive jaw surface adjusts electrosurgical energy delivery to tissue.  
   
   
       3 . The method of applying electrosurgical energy to tissue of  claim 2  wherein the pressure sensitive jaw surface adjusts electrosurgical energy delivery across the jaw surface in response to local tissue-engaging pressure.  
   
   
       4 . The method of applying electrosurgical energy to tissue of  claim 2  wherein a plurality of pressure sensitive jaw surface portions adjust electrosurgical energy delivery to adjacent engaged tissue in response to tissue-engaging pressure.  
   
   
       5 . The method of applying electrosurgical energy to tissue of  claim 1  wherein at least one pressure sensitive jaw closing mechanism adjusts electrosurgical energy delivery to tissue.  
   
   
       6 . An electrosurgical instrument comprising a jaw structure configured to engage tissue, and a pressure sensitive variable resistive system within the instrument for adjusting electrosurgical energy delivery in response to tissue-engaging pressure.  
   
   
       7 . The electrosurgical instrument of  claim 6  wherein the pressure sensitive system comprises a jaw element having the capability of reversibly transforming from a substantially insulative state to a substantially conductive state under pressure.  
   
   
       8 . The electrosurgical instrument of  claim 6  wherein said jaw element is at least a portion of a jaw surface.  
   
   
       9 . The electrosurgical instrument of  claim 6  wherein said jaw element is interior of a jaw surface.  
   
   
       10 . The electrosurgical instrument of  claim 6  wherein the pressure sensitive system comprises a polymeric material capability of transforming from a substantially insulative state to a substantially conductive state under pressure.  
   
   
       11 . The electrosurgical instrument of  claim 10  wherein the polymeric material is a conductively doped elastomer.  
   
   
       12 . The electrosurgical instrument of  claim 10  wherein the substantially conductive state has an impedance of less than 500 ohms/cm.  
   
   
       13 . The electrosurgical instrument of  claim 10  wherein the substantially insulative state has an impedance of greater that 50 ohms/cm.  
   
   
       14 . The electrosurgical instrument of  claim 10  wherein the substantially insulative state has an impedance of greater that 10,000 ohms/cm.  
   
   
       15 . The electrosurgical instrument of  claim 10  wherein the substantially insulative state has an impedance of greater that 100,000 ohms/cm.  
   
   
       16 . The electrosurgical instrument of  claim 10  wherein the polymeric material transforms from a substantially insulative state to a substantially conductive state under a pressure ranging between 0.5 psi and 500 psi.  
   
   
       17 . The electrosurgical instrument of  claim 10  wherein the polymeric material transforms from a substantially insulative state to a substantially conductive state under a pressure ranging between 5 psi and 250 psi.  
   
   
       18 . The electrosurgical instrument of  claim 6  wherein the pressure sensitive system comprises a pressure sensitive variable resistive link in a jaw closing mechanism.  
   
   
       19 . An electrosurgical instrument comprising a jaw structure configured to engage tissue, at least one jaw including a polymeric electrosurgical surface for applying electrosurgical energy to tissue, said at least one jaw includes an auxetic material for modifying a parameter or property of the electrosurgical surface.  
   
   
       20 . The electrosurgical instrument of  claim 19  wherein the auxetic material modifies compliant properties of the electrosurgical surface.